This is an example of a project that uses lots of layers. It's the Mother's Day Bouquet Card from the Crazy Cute Cards cartridge.
From the image it's difficult to work out how many colours of cardstock you'll need.
If you look at the Layers panel the colours are mixed up, so again it's hard to tell.
But, if you click on the Sync panel all the layers are sorted and you can easily see that there are seven colours used in the project.
You can of course minimise the number of colours used by combining two or more together. For example, if you wanted to combine the two cream shades you would click on the coloured rectangle of one and drag it up or down over the layer you want to combine it with.
The two layers have now been combined.
If you change your mind you can click the Undo button on the toolbar.
You can also see the number of colours once you click the Go button. ☺